1. Field of the Invention
The present invention relates to a motor mainly for use with the electric vehicle or the like, an electric vehicle and a hybrid electric vehicle.
2. Description of the Related Art
Conventionally, an internal combustion engine has generally been used as a prime mover for an automobile.
In recent years, air pollution, global atmospheric warming-up or the like have become an issue, and in terms of protection of global environment, development of an electric vehicle using an electric motor as its prime mover has been proceeding.
Among others, it is an electric vehicle such as a fuel-cell electric vehicle using a fuel cell as power supply and a hybrid electric vehicle using a battery as power supply that have been in the limelight for the last several years.
In the case of the former fuel-cell electric vehicle, since a motor is used for the power, there is no exhaust gas at all, both vibration and noise are exceedingly low as compared with the internal combustion engine, and in addition, a fuel cell having greater energy density than an ordinary battery is used as power supply, and therefore, there is the advantage that the fuel-cell electric vehicle has much longer travel distance per charging.
Also, as the latter hybrid electric vehicle, there has been developed a parallel hybrid electric vehicle or the like which directly drives drive wheels by combining a conventional engine, which is easy to supply fuel, with a motor, which is clean as energy, to use these power (Japanese Patent Laid-Open No. 59-63910 and U.S. Pat. No. 4,533,011).
In this respect, the entire disclosure of the Japanese Patent Laid-Open No. 59-63910 and U.S. Pat. No. 4,533,011 is incorporated herein by reference in its entirety.
As the structure of such a hybrid electric vehicle, there has generally been known a vehicle in which driving by the motor or driving by the engine is appropriately switched in accordance with various conditions such as traveling speed and travel area through the use of connection such as clutch to transmit driving forces (mechanical power) of those engine and motor to the drive wheels through power transmitting means such as transmission for traveling.
Also, in this sort of hybrid electric vehicle, the motor is caused to generate a driving force during, for example, acceleration of the vehicle, and it is added to an output from the engine to transmit to the drive wheels, whereby while acceleration performance to be required of the vehicle is being secured, the engine""s output is restrained, and reduction in fuel consumption and exhaust gas of the engine is planned.
Further, in the case of the hybrid electric vehicle, during, for example, deceleration of the vehicle, it is common practice to drive the motor as a generator for regenerative power generation by means of kinetic energy of the vehicle to be transmitted to the motor from the drive wheels through the power transmitting means, and to recover the regenerative power generation out put thus obtained for accumulation. Concretely, the recovered power is directly accumulated in electric energy storing means itself such as the power supply battery for the motor.
In contrast, a method and structure for recovering and accumulating regenerative power in the case of the fuel-cell automobile are different from the case of the hybrid electric vehicle.
Concretely, the fuel cell itself is provided with an auxiliary cell or the like for exclusive use in storing regenerative power because it is not capable of directly receiving any regenerative power structurally.
As a motor for power for such a fuel-cell automobile, however, a small-sized, high-output, high-efficiency interior permanent magnet motor is optimum, but when a rotor of the motor is rotating during traveling or during regenerative control, a permanent magnet rotor generates generated voltage. This generated voltage is applied to the power supply (fuel cell) through an invertor as reverse generated voltage. Since the fuel cell is vulnerable to overvoltage and is not capable of directly receiving any regenerative power structurally as described above, an auxiliary cell or the like are connected to return the regenerative power (see FIG. 4).
In this respect, it is possible in principle to prevent the reverse generated voltage from the motor from being applied to the fuel cell by separately providing switching means between the motor and the fuel cell to electrically separate both, but here, the description has been made of a general case where such switching means is not provided.
Therefore, the reverse generated voltage is also applied to the fuel cell during ordinary traveling or during regenerative control. However, since the motor does not rotate at much high speed during ordinary traveling or during regenerative control at ordinary speed, the reverse generated voltage generated by the motor has a low value, and there arises no problem even if the reverse generated voltage is applied to the fuel cell itself.
However, during traveling at high speed, that is, when the motor is rotating at high speed, high reverse generated voltage is applied to the fuel cell. Thus, when a value of such reverse generated voltage exceeds the cell voltage, the motor becomes unable to rotate, and therefore, when the motor should be rotated at higher speed, so-called xe2x80x9cfield weakening controlxe2x80x9d is performed as control to advance current phase, to thereby restrain generated voltage generated to be low.
If, however, a power control unit such as an invertor should be out of order and become unable to be controlled during such traveling at high speed, considerably high reverse generated voltage would be applied to the fuel cell, which is very dangerous.
On the other hand, although supposing such a trouble case, it is possible to use a motor, in which low generated voltage is generated, in order to make the generated voltage low, it is necessary to reduce a number of flux interlinkage of the stator winding. Therefore, it is necessary to use a permanent magnet having lower characteristic, or to reduce an amount of permanent magnet used or to reduce a number of turns of the stator winding, and therefore, there is a problem that the motor becomes a low-output, low-efficiency and low-performance motor, through which high input current flows (first problem).
On the other hand, in the above-described hybrid electric vehicle, when auxiliary output is caused by driving the motor during acceleration of the vehicle, the motor consumes a comparatively large amount of electrical energy of electric energy storing means of supplying electric power such as the battery. Therefore, when the motor is caused to generate auxiliary output in a state in which a small amount of electric energy is stored in the electric energy storing means during acceleration of the vehicle, during acceleration of the vehicle, the electric energy storing means is prone to be deteriorated.
Accordingly, in such a case, it is considered preferable to place the motor in an operation-stopped state (energization-interrupted state of motor) without generating auxiliary output by the motor.
Also, during cruising (during constant-speed traveling) of the hybrid electric vehicle, it is possible to travel the vehicle without a hitch only with the output of the engine concerned while fuel consumption of the engine is being made sufficiently low, and since consumption of electric energy of the electric energy storing means more than necessary is prone to deteriorate the electric energy storing means, the motor is generally caused to be in an operation-stopped state.
In the conventional hybrid electric vehicle, however, when the vehicle is traveling through the use of the engine output, the rotor of the motor is adapted to always rotate in synchronization with an output shaft of the engine. The rotor of the motor is directly coupled to the output shaft of the engine, or is connected to the engine output shaft through a gear or the like (see, for example, Japanese Patent Laid-Open Application Nos. 8-193531 and 9-14360).
In this respect, the entire disclosure of the Japanese Patent Laid-Open Nos. 8-193531 and 9-14360 is incorporated herein by reference in its entirety.
For this reason, in the conventional hybrid electric vehicle, when the motor has been caused to be in an operation-stopped state in accordance with a traveling state of the vehicle, an energy-stored state (for example, remaining capacity of the battery) or the like of the electric energy storing means during traveling of a vehicle using the output of the engine, the rotor of the motor has become a load of the engine, which has become one factor for increasing fuel consumption of the engine.
In the case where a magneto electric motor is particularly used as a motor, when a rotor of the electric motor directly coupled to a driving shaft of the vehicle or a driving system rotates, magnetic flux, which interlinks with a stator of a permanent magnet provided on the rotor, causes iron loss in the stator of the electric motor.
Since it occurs even if the motor is not energized, this iron loss lowers the engine efficiency because the motor generates heat. Thus, the travel distance per charging is shortened, and therefore, this is a problem of the hybrid electric vehicle (second problem).
As a solution to such a problem, it seems to be considered to use a reluctance motor using no magnet at all, but when the reluctance motor is used, the size of the motor becomes comparatively large in order to obtain required output.
The hybrid electric vehicle has no room as the vehicle space because it is mounted with two driving systems: internal combustion engine(ICE) and electric motor as a traveling source. Therefore, it is not desirable as described above that the motor becomes large in size, but it is difficult to use the reluctance motor.
Further, if the motor is not properly controlled due to malfunction of a micro computer control circuit, when the hybrid electric vehicle is traveling at high speed only by the output of the ICE, the following problem will occur. More specifically, since the rotor of the motor is adapted to always rotate in synchronization with the output shaft of the engine structurally, the motor is driven as a generator for regenerative power generation so that excessive voltage is applied to the electric energy storing means such as a power supply battery. In this case, particularly a sufficient amount of electric energy stored by the electric energy storing means leads to deterioration or damage of the electric energy storing means, which possibly may result in a dangerous state (third problem).
The present invention has been achieved in order to solve the above-described conventional problem, and is aimed to provide a small-sized, high-output and high-efficiency motor capable of restraining generated voltage generated to be equal to or less than, for example, voltage of a fuel cell even when the rotor is rotating at high speed during high-speed traveling of, for example, an automobile (electric vehicle such as a fuel-cell automobile, or hybrid electric vehicle), and moreover the output of which does not lower.
Also, it is an object of the present invention to contribute to enhancement of performance and safety of a fuel-cell automobile using such a motor.
Also, the present invention has been achieved in the light of such conventional problems, and is aimed to enable efficiency and safety in a hybrid electric vehicle system to be enhanced and secured respectively.
One aspect of the present invention is a hybrid electric vehicle, comprising:
a rotor, comprising a plurality of first rotator portions, each having a permanent magnet, and one or a plurality of second rotator portions, each having magnetic saliency, said first and second rotator portions have been arranged adjacent to each other in a direction of a rotating shaft; and
a stator which generates a magnetic field for driving said rotor when electric current is supplied.
A first motor according to the present invention is, because of the above-mentioned structure, capable of reducing an amount of permanent magnet of the entire rotor to restrain occurrence of generated voltage by making part of the rotor into the reluctance motor even if the rotor rotates at high speed during high-speed traveling. Therefore, even if an electric power converting unit such as an invertor should be out of order and become unable to be controlled, there is no problem in safety because the reverse generated voltage to be applied to the fuel cell is restrained to be equal to or less than its cell voltage.
Also, since it is provided with a permanent magnet, a first rotator portion can be made into a high-output and high-efficiency motor. Further, the first rotator portion has saliency by embedding a permanent magnet therein, and is capable of utilizing the reluctance torque in addition to the magnet torque, and a higher-output, and higher-efficiency motor can be obtained. In this respect, a second rotator portion is constructed to have magnetic saliency by providing the rotator with irregularity geometrically or providing a slit within the rotator or the like.
Another aspect of the present invention is the motor, wherein said plurality of first rotator portions are not arranged adjacent to each other.
A motor according to the present invention is, because of the above-described structure, capable of raising a salient pole ratio of the second rotator portion to thereby increase reluctance torque caused in the second rotator portion by causing leakage flux of a permanent magnet further disposed in the first rotator portion in addition to the above-described effect to go round to the second rotator portion from both sides to magnetically saturate the second rotator portion.
Therefore, the motor can be made into a small-sized, high-torque, high-output and high-efficiency motor at low generated voltage, and the motor size can be also further reduced.
Also, when there are a plurality each of the first rotator portions and the second rotator portions, magnetic saturation is performed by leakage flux as described above, and a number of the second rotator portions are improved in salient pole ratio and reluctance torque, and therefore, the motor becomes a higher-torque, higher-output, higher-efficiency motor at low generated voltage, and can be further miniaturized.
Still another aspect of the present invention is the motor, wherein said first rotator portion and said second rotator portion are magnetically combined.
A motor according to the present invention is, because of the above-described structure, capable of raising a salient pole ratio of the second rotator portion to thereby increase reluctance torque caused in the second rotator portion by causing leakage flux of a permanent magnet further disposed in the first rotator portion in addition to the above-described effects to go round to the second rotator portion to magnetically saturate the second rotator portion.
Therefore, the motor can be made into a high-torque, high-output and high-efficiency motor at low generated voltage, and the motor size can be also miniaturized.
Yet another aspect of the present invention is the motor,
wherein said second rotator portion has a shape of having a plurality of inverted-circular arc-shaped notches on a circumferential portion of a circular plate or a cylindrical column, and
a full or partial contour portion of said notch is provided at a position whereat said full or partial contour portion opposes to said permanent magnet.
A motor according to the present invention is, because of the above-described structure, capable of raising a salient pole ratio of the second rotator portion to thereby increase reluctance torque caused in the second rotator portion by causing main magnetic flux of a permanent magnet disposed in the first rotator portion in addition to the above-described effect to flow into the stator side, causing leakage flux to go round to the second rotator portion effectively to magnetically saturate the second rotator portion.
Therefore, the motor can be made into a high-torque, high-output and high-efficiency motor at low generated voltage, and the motor size can be also miniaturized.
Still yet another aspect of the present invention is the motor, wherein said first rotator portion and said second rotator portion are arranged adjacent to each other in such a manner that current phases for generating their both maximum torque become actually in the same phase.
A motor according to the present invention is, because of the above-described structure, capable of being made into a higher-torque, higher-output and higher-efficiency motor at low generated voltage by causing current phases for generating respective maximum torque of the first rotator portion and the second rotator portion to be in the same phase with each other in addition to the above-described effects. The motor size can be also further miniaturized.
A further aspect of the present invention is the motor, wherein said stator has a stator winding of distributed winding or a stator winding of concentrated winding.
A motor according to the present invention is, when the stator has a stator winding of distributed winding, capable of being made into a motor having small cogging torque and torque ripple, and on the other hand, is, when the stator has a stator winding of concentrated winding, capable of being made into a high-torque motor, a motor-installing method of which is simple and easy.
A still further aspect of the present invention is a driving unit equipped with a motor, and a fuel cell as power supply for said motor.
A driving unit according to the present invention is, as described above, capable of being made into a small-sized, high-output and safe driving unit having longer travel distance per charging by combining a small-sized, high-torque, high-output and high-efficiency motor at low generated voltage with a fuel cell.
A yet further aspect of the present invention is an electric vehicle comprising a driving unit.
An electric vehicle according to the present invention is, because of the above-described structure, capable of being made into a small-sized, high-output and safe fuel-cell electric vehicle having long travel distance per charging.
A still yet further aspect of the present invention is a hybrid electric vehicle, comprising:
electric energy storing means of storing electric power;
a motor for driving through the use of electric power of said electric energy storing means;
motor control means of controlling said motor;
a power regulator provided between said motor and said electric energy storing means, for converting their both power;
an engine for driving using fuel; and
engine control means of controlling said engine, wherein said hybrid electric vehicle being traveling through the use of a driving force of said motor and a driving force of said engine, and
wherein said motor has:
(1) a rotor comprising a first rotator portion having a permanent magnet and a second rotator portion having magnetic saliency coupled in the direction of a rotating shaft; and
(2) a stator which generates magnetic a field for driving said rotor.
An additional aspect of the present invention is the hybrid electric vehicle, wherein said first rotator portion and said second rotator portion are coupled at such a mechanical angle that a current phase with which maximum torque of said first rotator portion occurs, and a current phase with which maximum torque of said second rotator portion occurs become actually in the same phase.
A still additional aspect of the present invention is the hybrid electric vehicle, further comprising:
abnormality monitoring means of monitoring occurrence of an abnormal state in said electric energy storing means; and
power regulator control means of controlling an operation of said power regulator on the basis of a signal from said abnormality monitoring means.
A yet additional aspect of the present invention is the hybrid electric vehicle, wherein said abnormality monitoring means has at least one means, of voltage monitoring means of monitoring voltage of said energy storing means, current monitoring means of monitoring current of said energy storing means, temperature monitoring means of monitoring temperature of said energy storing means, and power regulator monitoring means of monitoring abnormality of said power regulator.
A hybrid electric vehicle system according to the present invention having the above-described structure has a motor equipped with a rotor comprising a first rotator portion having a permanent magnet and a second rotator portion having magnetic saliency coupled in a direction of a rotating shaft, and a stator, which generates a magnetic-field for driving the rotor by supplying current, and is mounted on the vehicle with the output from the motor as the traveling source. Thereby, as the motor output, for example, leakage flux of a permanent magnet disposed in the first rotator portion is caused to go round to the second rotator portion 701 to magnetically saturate the second rotator portion, whereby a salient pole ratio of the second rotator portion is raised to thereby increase reluctance torque caused in the second rotator portion. Thus, high output can be realized, and therefore, even when the motor is rotated by the engine in a state in which the motor is in an operation-stopped state while the equal output to the hybrid electric vehicle system using a conventional magneto motor, is being maintained, an amount of magnet to be used for the rotor is reduced. Accordingly, it is possible to restrain generated voltage from being generated, and to reduce the iron loss.